C++ fundamentals · Lesson 3 of 21

Operators and input

%, ++, compound operators, cin, and operator precedence.

8 minutes3 games

The arithmetic operators + - * / work as in maths, plus %, which gives the remainder: 17 % 5 is 2. It's very handy: check even or odd (n % 2 == 0), or take the last digit (n % 10).

C++

#include <iostream>

int main() {
    int xp = 10;
    xp += 5;      // xp = xp + 5
    xp *= 2;      // xp = xp * 2
    xp++;         // xp = xp + 1
    std::cout << "xp = " << xp << "\n";

    int minutes = 135;
    std::cout << minutes / 60 << "h " << minutes % 60 << "m\n";
    std::cout << (1234 % 10) << " is the last digit\n";
    return 0;
}

Step by step1 / 4

▶int xp = 10;
2xp += 5;
3xp *= 2;
4xp++;

Variables

Output

…

Input with cin

C++

#include <iostream>
#include <string>

int main() {
    std::string name;
    int age;
    std::cout << "Name and age? ";
    std::cin >> name >> age;           // reads two values separated by spaces
    std::cout << "Hi " << name << ", next year you'll be " << age + 1 << "\n";
}

The runner here can't take typed input, so try this one on your machine. std::getline(std::cin, line) reads a whole line, spaces included.

What's the output?

#include <iostream>
int main() {
    int a = 5;
    int b = a++;
    int c = ++a;
    std::cout << a << " " << b << " " << c << "\n";
}

What will this code print?

Quick question

What is 2 + 3 * 4 % 5?

Exercise

You have int seconds = 3725. Print it as 1h 2m 5s.

Expected output: 1h 2m 5s

C++

#include <iostream>

int main() {
    int seconds = 3725;
    
    return 0;
}

Learn more from

Played 0 of 3 games

C++